Effects of computer mouse design and task on carpal tunnel pressure

Computer mouse use has become an integral part of office work in the past d ecade. Intensive mouse use has been associated with increased risk of upper extremity musculoskeletal disorders, including carpal tunnel syndrome. Sus tained, elevated fluid pressure in the carpal tunnel may play a role in the pathophysiology of carpal tunnel syndrome. Carpal tunnel pressure was meas ured in 14 healthy individuals while they performed tasks using three diffe rent computer mice. Participants performed a multidirectional dragging ('dr ag and drop') task starting with the hand resting (static posture) on the m ouse. With one mouse, an additional pointing ('point-and-click') task was p erformed. All mice were associated with similar wrist extension postures (p = 0.41) and carpal tunnel pressures (p = 0.48). Pressures were significant ly greater during dragging and pointing tasks than when resting the hand (s tatic posture) on the mouse (p = 0.003). The mean pressures during the drag ging tasks were 28.8-33.1 mmHg, similar to 12 mmHg greater than the static postures. Pressures during the dragging task were higher than the pointing task (33.1 versus 28.0 mmHg), although the difference was borderline non-si gnificant (p = 0.06). In many participants the carpal tunnel pressures meas ured during mouse use were greater than pressures known to alter nerve func tion and structure, indicating that jobs with long periods of intensive mou se use may be at an increased risk of median mononeuropathy. A recommendati on is made to minimize wrist extension, minimize prolonged dragging tasks a nd frequently perform other tasks with the mousing hand.